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Home > Senior Science > Core > Information Systems > Information Systems: 1. Information systems and energy transfer

9.4 Information Systems: 1. Information systems and energy transfer

Extract from Senior Science Stage 6 Syllabus (Amended October 2002).© Board of Studies, NSW.

[Edit: 28 Aug 08]

Prior learning:
Stage 4, Outcome 4.6 (core content 4.6.1, 4.6.3, 4.6.4, 4.6.5, 4.6.9), Stage 5, Outcome 5.6 (core content 5.6.1, 5.6.3, 5.6.4,) Outcome 5.12 (core content 5.12 c, d).

Background: Recent technological advances in fibre optics mean that it is now practical to use light as a message carrier. Because light has a much higher frequency than radio waves, it is able to carry much more information per second. The replacement of the copper wire-based telephony system with light carrying, optical fibres will enable every household to access multiple, two-way voice, data and video channels, as well as enable business and commerce to move more information per second between offices than ever before. Video conferencing will become a daily event between offices around the world, and videophones at home will become a reality.

The switch from analog to digital information coding systems in the telecommunications industry has allowed the use of sophisticated computer compression processes, thus ensuring that the least amount of code is needed to reproduce a desired message. The same technology has enabled the development of video CDs and digital video discs (DVDs).

Large-scale integration (LSI) has enabled computer circuitry to be reduced in size, weight and energy consumption to become the basis for satellite-based global networks for the delivery of voice (mobile phone), data, video and location information (global positioning systems, or GPS).

The application and refinement of the above technological advances in a short time span (since the 1950s) has had an enormous impact on every day life in Australia.

recall phenomena and events where different forms of energy are used

• Energy is involved when a change to the physical or chemical state of a material object occurs. Many phenomena are energy carriers (because they have the capacity to cause changes when they encounter other objects). When we are interested in their capacity to make a change, we describe the phenomena as a form of energy. Energy exists in many different forms, e.g. electromagnetic radiation, sound, thermal, electrical and potential.
• Electricity is a phenomenon related to the movement of electrically charged particles (electrons or ions). An electric current is the movement of electrons through materials and, because of their nature and their movement, they are energy carriers. Batteries convert chemical (potential) energy to electrical energy in many communication devices.
• Electromagnetism is used to produce motion from electric currents. Electromagnetism is used to make sound from earpieces, electric bells and loudspeakers.
• Semiconductors are materials whose resistivity is between that of a conductor and an insulator. These devices are widely used in electronic circuits found in many communication devices. Controlling excess thermal energy is important to ensure the proper functioning of circuits containing semi-conductor devices, such as LSI chips.
• Cathode rays (a continuous stream of electrons) have a number of applications from the production of X-rays to the creation of images in cathode ray tubes (CRTs) that are critical components of many television sets and computer monitors.

identify a range of information systems used daily  

• These days, words, music and images are transmitted around the world via cable (copper wire and optical fibre), microwave, radio and satellite-based communications systems.
• Information systems in daily use include the following. Some of them use a combination of electric and electromagnetic carriers to achieve their purposes:

Bar codes Body language Cable television CB radio Compact discs (CD) Digital versatile discs (DVD) Facsimile Film International symbols Internet and intranet Laser video systems Mobile phone: digital and analog Multimedia interactive video

Print media Public switched telephone networks (PSTN) Radar Satellite Short message service (SMS) Sign language Sonar Sound Telemetry Television and teletext Touch, smell, taste Video and video tape

outline the basic pattern of the information transfer process as:

• code common to both parties
• message
• transmission of coded message
• decoder

Code common to both parties

• Pictures, words and music are examples of codes. The sender deliberately uses agreed conventions or codes, which must be learned, to construct a message.

Message

• A message to be transferred electronically may have to be coded again, so that it can alter the carrier current or wave in a systematic and consistent way. By international agreement, the two ways of doing that are by either analog or digital means. Nowadays, digital methods are preferred to analog because they are more reliable.

Transmission of coded message

• Once the carrier current or wave has been coded, it is sent to the required destination. Modern communication systems use either (or both) an electric current or electromagnetic waves to carry messages.

Decoder

• Two steps are now involved in extracting the message. The first detects and separates the code from the carrier current or wave. The second involves converting that code into a form that the receiver’s senses can detect and interpret to make meaning. Once the message has been decoded and understood, communication has taken place.

classify information systems as

• verbal and nonverbal
• short distance and long distance
• electronic and non-electronic

Background Verbal communication involves the use of a language (common code) that is spoken or written by the sender to the receiver. Nonverbal communication does not involve spoken or written language. Nonverbal communication may take place directly in the presence of the receiver or via a communication device. Short distance communication may take place in the presence of the receiver or within their environment. Long distance communication may be defined by the type of system to be used, e.g. interstate telephone calls are considered to be long distance. Some systems are able to communicate over vast distances, e.g. unmanned space probes are able to send data and pictures back to earth. Electronic communication (developed in the 20th century), involves the controlled use of an electric current by devices such as thermionic valves, semiconductors, transistors and other components. Integrated circuits found in many modern communication devices may contain many thousands of such components built into a single slice of silicon.

• Communication systems can be classified in a number of ways. Consider the following systems: talking (directly with another person), body language, public address systems, mobile phone, cable television, radar, sonar,Internet. In the tables presented below, these devices are classified to show how differently each is classified depending on the criteria applied. Notice that some systems can involve both verbal and nonverbal at the same time.

  verbal	nonverbal
  talking public address systems mobile phone cable television Internet	body language radar sonar cable television Internet

  
   

  short distance	long distance
  talking public address systems body language sonar mobile phone	cable television radar Internet mobile phone

  
   

  electronic	non-electronic
  public address systems mobile phone cable television radar sonar Internet telephone system	talking body language

gather and process information from secondary sources to develop a timeline of communication systems introduced to society and use the available evidence to analyse the impact these systems have had on society and predict possible future directions in communication technologies

• Information may be gathered from reference books, such as encyclopedias and communication technologies texts that contain historical information.
• When processing your information, you should list developments chronologically to show when each form of communication was introduced and the subsequent developments that took place. Placing information in a scaled timeline may illustrate trends and patterns that will assist in your analysis of the impact of communication systems on society.
• Use the information to analyse the impact these systems have had on society by:
  • considering the widespread effect on the way people lived and worked over the years following the introduction of each system
  • describing how each system is interconnected with other forms of communication
  • proposing logical connections between the introduction of each communication systems and changes in society
  • making and justifying a generalisation about the impact of such systems.
• Predict possible future directions in communication technologies by:
  • identifying trends in such things as the size of the technology, the uses of it, the amount of information it can carry, the people who use it
  • making statements about how communication technologies could be used in the future, based on these trends
  • thinking creatively. Some people see a link between modern technologies and ideas from science fiction. Try to justify any fictitious ideas, such Dick Tracey's radio-watch or Maxwell Smart's shoe phone, as now being feasible.

gather and process first-hand and secondary information on the basic pattern of the information transfer process in the following systems:

• land connected telephones
• mobile phones
• television
• radios
• Compact Disc players

to outline features that the systems have in common and use available evidence to discuss the applications of these systems

• You need to gather and process information from your own investigation of all of the systems identified in the list. For example, you may choose to examine and operate a telephone or mobile phone and a CD player. You could then make observations and describe each step of the information transfer process for these devices. It might be useful to identify the enery transformation processes for each system as the information is required for another syllabus dot point. You may not be able to observe every step of the process, such as what occurs at the central mobile exchange for a mobile phone system.

Be clear about the processes you are describing:

An information transfer process refers to: code --> message --> transmission --> decoder

An energy transfer refers to moving one form of energy, e.g. electrical wires carrying electricity from power station to your home

An energy transformation refers to changing a form of energy into another form, e.g. electrical --> KE

• You will need to gather and process from secondary sources some information about the features of each system listed. Use sources such as reference books, magazines that provide consumer information about electronic products, such as hi-fi and video cameras, CD-ROMs, industry product information and the Internet (try entering into a search engine popular brand names for electronic communication equipment, like Sony, Nokia, Panasonic or Samsung).

• It may be useful during processing to compile your information in a table so that a comparison of what is common in the transfer–transformation processes used in the devices can be made. Use available evidence to discuss the transfer–transformation process, making sure you correctly use scientific terms and principles. Remember that the transfer process may use components of the electromagnetic spectrum (e.g. visible light, microwaves, UHF, VHF, FM & AM radio, and short-wave radio) electrical pulses, sound, electronic circuits, laser light or fibre optic cable.

identify the transformation of energy at each stage of information transfer in the following devices

• land connected telephones
• mobile phones
• television
• radios
• Compact Disc players

Background Energy exists in many different forms. It can be moved from place to place (energy transfer) or it can be changed between forms (energy transformation), However, energy cannot be created or destroyed (law of conservation of energy). All communication devices involve energy transfer and transformation. Energy may be stored (potential), e.g. mobile phone batteries or in the form of movement (kinetic), e.g. sound.

The following flow charts show the sequence of energy transformations at each stage of information transfer in the identified devices. 

• Energy transformations in land connected telephones
  KE (sound) ----> electrical  ----> KE (sound)
• Energy transformations in a mobile phone system

  
   
  

• Energy transformations for a television system 

  

• Energy transformations for radios
  Sound ----> electrical ----> Radio waves ----> electrical ----> sound
   
• Energy transformations for Compact Disc players
  To provide the rotation of the disc: Electrical ----> KE (movement)
  For the sensing system: Light ----> Electrical ----> KE (sound)

discuss the advantages of using a range of information systems

• Some systems lend themselves better to specific applications. For example, the coding systems used in FM radio are not destroyed by natural phenomena, such as electrical storms, during transmission. AM radio can be transmitted over greater distances than FM radio but the signals may be interfered with by electrical storms and other nearby communication equipment.
• Access to a choice of systems is inherently more reliable. For example, international telephone calls can go via cable or satellite. If one fails, the other can take over.
• If you are an advertiser, the choice of radio, TV, print or Internet means that your message is more likely to be received and appropriately interpreted by the receiver.